次生维管组织由维管形成层、次生韧皮部和次生木质部组成，维管形成层细胞向外侧分化形成次生韧皮部，向内侧分化形成次生木质部，从而形成了有序的次生维管组织模式。本项研究将采用植物离体和活体剥皮再生实验系统，以普通杨树和生长素与细胞分裂素代谢、信号传导相关转基因杨树为材料，研究生长素、细胞分裂素在杨树剥皮再生过程中的分布动态、外源生长素与细胞分裂素以及生长素运输抑制剂对次生维管组织再生的影响、内源生长素与细胞分裂素合成、运输或信号转导改变对次生维管组织再生的影响，并进一步研究这些影响的发生机制，在此基础上探讨生长素与细胞分裂素调控植物剥皮再生过程中次生维管组织模式重建的机理。本项研究将为全面认识植物组织器官再生、次生维管组织发育的调控机制提供实验资料，也可为动物组织再生研究、再生医学研究提供借鉴。

Secondary vascular tissues, including cambium, secondary phloem and secondary xylem, play key roles in plant growth and development. The cambium meristem cells divide and differentiate into the secondary phloem outside and the secondary xylem inside, all of them form the secondary vascular tissue pattern. After bark girdling in trees, for example, in Populus, the secondary phloem and cambium are removed from the trunk along with the bark,and the secondary vascular tissue pattern is broken. While, the wounded tree will regenerate new bark and rebuild the pattern in about two weeks under certain conditions. In this study, the bark regeneration after girdling in vivo and in vitro will be investigated using wild type and transgenic poplar trees in order to reveal the regulation mechanisms of auxin and cytokinin on the secondary vascular tissue pattern rebuild during bark regeneration. Distribution dynamics of auxin and cytokinin during the process of bark regeneration and their roles on bark regeneration, roles of exogenous and endogenous auxin and cytokinin on expression pattern of key genes of secondary vascular tissue pattern formation will be also studied. The results will provide experimental data for understanding the mechanisms of plant regeneration and vascular tissue development.